1. Overcrowding the pan.
2. Undersalting the water.
3. Using extra virgin olive oil to cook ~everything.~
4. Measuring dry ingredients in a liquid measuring cup.
When it comes to baking, measuring ingredients correctly is key. For dry ingredients, your best bet is using the spoon-and-level method, where you'll scrape off the overflow — leaving behind a level surface, and an accurate measurement. (Want to get even more ~precise~? Use a kitchen scale: Here's a solid option for $10.)
5. Putting cold meat in a hot pan.
Or grill, or oven. Letting cold meat come up to room temperature before tossing it on the heat means it'll cook more evenly — and you're more likely to avoid the outside being overdone, while the inside isn't quite there yet.
6. Or putting hot food in a cold fridge.
Whether it's steaks, soups, or sauces, you want to make sure food has had enough time to cool down before tossing it in fridge or freezer. (One way to expedite the process? A DIY ice bath.) More info on that — and on why you shouldn't put hot food directly into a cold fridge — at The Kitchn.
7. Ignoring the ~order of operations~ when using a Crock-Pot.
Crock-Pot drop-and-go dinners are a glorious thing, but order does matter. You'll want to add dairy products (like milk or cheese) at or near the end, because cooking them at high heat for a long period of time can cause them to curdle. The same goes for things that just need to be warmed through: like ready-made pasta, cooked beans, and small vegetables. Add 'em last.
8. Using a non-stick pan at all times.
9. Adding garlic too early.
10. Sautéing greens or mushrooms that are still wet.
11. Not letting meat rest after cooking.
It's always worth it to wait a few extra minutes before slicing into a cut of meat. The juices re-distribute, and you're ultimately left with a more delicious bite. (You also buy yourself time to crack open a drink in the meantime, so win-win.)